Wing structure



May 1, 1934. E, B, CARNS 1,956,823

WING STRUCTURE I Original Filed June 15, 1929 2 Sheets-Sheet, 1

y 1934. E. B. CARNS 1,956,823

WING STRUCTURE Original Filed June 13, 1929 2 Sheets-Sheet, 2

l atentecl May 1, 1934 UNl'l'ED STATES PATEN E' FFifiE CairnsDevelopment Company, Wilmington,

Del, a corporation of Delaware Application .lune 13, 1929, Serial No.370,695 Renewed August 15, 1933 1d illairns.

My invention relates to improvements in aircraft structures and moreparticularly to the wing or airfoil structure of an aircraft.

My invention is particularly intended to give a strong rigid structurehaving a minimum weight. I accomplish this by a means which is extremelysimple, in which there is no waste metal in any of the parts and inwhich there are no unnecessary structural elements.

My invention is further intended to produce a wing frame which tapers inwidth and thickness, that is, a double tapered wing and also a structurein which the structural elements taper in cross section, that is, aregradually reduced in cross section, and in which the structural elementsare made lighter progressively toward the wing tips.

My invention is further intended to produce a structure which is easy toproduce due to the simplicity of the parts, their availability in theopen market, and which are also adaptable to commercial production on aquantity basis. In accomplishing these ends according to my inventionthe points at which the elements must be fastened are easily accessiblethus allowing not riveting and eliminating the disadvantages of coldriveting. My invention further provides a structure in which the partsmay be fastened to gether without weakening any of the elements.

These objects are attained by placing the inerbracing in such a mannerthat they represent he resultants of the stresses in a wing strucure. Bythis means 1' have eliminated all unnecessary elements. Carrying outthis analogy, my interbracing represents the diagonals of cubes, theother edges of the cubes representing the various stress vectors.

" 'ing more particularly to the drawings:

Figure 1 represents a perspective view of a broken portion of mystructure:

- re 2 is a view taken at 2-2 of Figure 1; -re 3 is a View taken at 3-3of Figure 1;

Figure 4 is a View taken at 4 4 of Figure 1;

Figure 5 is a broken detail of unasseinbled brace elements;

Figure 6 is a detail of a lock washer;

Figure '7 is a modified form of rib structure and fastening;

Figure 8 is a side view partly in cross section of a spar member; and

' re 9 is a perspective view showing the wing cover .ig.

in Figure l the 11., per spar members 1 and the lower spars 2 are heldin spaced relationship by means of the interbraces 3. These spars are ofa generally angle bearn cross section and are of tapered constructiontapering both in width of the langes and in thickness of the metal. Theyalso taper in their spaced relationship gradually approaching each otheras they approach an exty of structure. The interbraces 3 are preflyz-beams but may be of other suitable type. ey are formed with ends 4 asshown in Figure 5. may easily be done by trimming oil a portion of aflange and then bending the end to the form shown, or the braces may becast or worked in any other manner to this form. The ends of theseinterbraces are designed to fit in one another as shown at 5, Figures 1and 4. The inner flange 6 is placed under the edge of the spars 1 and 2as shown in Figure 3. These interbraces are fastened together by rivetsat '7, and the two overlapped ends .are fastened to the spars 1 and 2 bymeans of the bolt 8. The angles of the upper and lower spars open intothe structure. The angle of the sides of the spars is such that bothends of the interbraces lie flat against the sides of the spa-rs. Thenut 8 on the bolt 8 is held fixed by means or the washer 9, a plan viewof which is shown in Figure 6. This washer is bent so that it fits inthe angle of the spars 1 and 2 and is perforated on each end at 10 whichallows the boi to pass through it. After the nut 8 has been screwedtight on the bolt 8 the tabs 11 are bent up holding the nut in fixedposition.

The cross ribs 12 run transverse to the spar members. ihese ribs may betapered in all dimensions as they approach an extremity of thestructure, for instance, the leading or trailing edge of a wing. Thecross ribs arev cut away as shown at 13, Figure 2, so that the sparmembers may be recessed in it and a snug fit thus made. The ribs arefastened to the bolt 8 by means of the bolt 14 which passes through therib and the hole 15 in the bolt 8 situated inside of the channel. Bolt 8may be cut away as shown at 16, Figure 4, eliminating a certain amountof metal which is unnecessary.

Figure 7 discloses a modification of a rib and method of fastening inwhich 17 designates a T- beam type of rib. This rib is cut away at 18allowing it to fit snugly over the spar member and is fastened to thespar by means of bolt 8. However, in this type of construction the webof the rib may be placed within the recess 16 of the bolt 8 and heldfast by passing the bolt 14 therethrough.

Figure 8 shows the tapered construction of the spars 1 and 2, l9representing one flange showing its taper towards the tip and 20designating a cross section of the other flange showing that this crosssection also decreases toward the tip.

It can be seen from the structure disclosed that the elements have allbeen simplified to an extreme degree and that they are of such a typeand design as to facilitate easy manufacturing on a commercial scale.Further it can be seen that the methods of fastening these elementstogether are such that they are not weakened. The ribs and interbracesare fastened to the spars in such a manner that only a minimum number ofholes are necessary in the spars. For this reason the spars may be madelighter inasmuch as it is not necessary to use extra metal to counteractthe weakness due to the holes necessitated in fastening the elements tothe spars. The interbraces are fastened together separate from the spar.The ribs are fastened to the same bolt which fastens the interbraces tothe spar.

My structure is an extremely simple one to assemble for the interbracesmay be easily riveted together at a point distant from where the structure is to be assembled. These braces, spars and ribs may then bequickly assembled by means of a single bolt at each point ofintersection. I have been able to obtain such a simple structure byresolving all of the stresses and using interbracing only as theresultant of these stresses. In this way I have a statically determinedstructure where every stress is taken up at the proper point anddistributed over the entire structure. I have thus been able to obtain alight rigid structure of great strength and with locked stresses.

My structure may be covered in the manner disclosed in Figure 9. I haveshown in this figure the structure and covering adapted to a wing but itis, of course, applicable to any wind-exposed surface. The coveringconsists of the sheet or sheets 21, 21 21 21, 21 These sheets areoverlapped as shown at 22, the overlapping of course, being towards thetrailing edge. The sheet which at the point of overlapping is placedunderneath is placed over the sides of the spars 1 as shown at 23. Theedge of this sheet has tabs of which one is shown extending at 24. Thesetabs are bent under the edges of the spars l and 2 holding the sheetfirmly in place. The upper overlapping sheet is then fastened by meansof rivets or otherwise to the undersheet as shown at 25. The coveringsheets may also be fastened if desired transversely to the ribs 12 byscrews preferably of the type shown in my copending application SerialNo. 179,987, filed March 31, 1927. In this manner a strong, tightwind-exposed surface is obtained without the necessity as is the usualcase, of weakening the structure members by drilling them for thefasteners with which to hold the covering to the frame.

To those skilled in the art it is obvious that my structure is adaptableto many other portions of an aircraft besides that of a wing structure.The structural design of certain elements may also be changed withoutdeparting from my invention. I, therefore, do not wish to be limited bymy specification and drawings, but only by the prior art and theappended claims.

What I claim is:

1. In an aircraft structure upper and lower tapering spars in staggeredrelationship, diagonal interbraces connecting said spars, and upper andlower tapering ribs in staggered relationship connected to said sparsand interbraces.

2. In an aircraft structure upper and lower tapering spars in staggeredrelationship, diagonal interbraces having ends meeting at said spars,and upper and lower tapering ribs in staggered relationship connected tosaid spars and interbraces.

3. In an aircraft structure upper and lower tapering spars in staggeredrelationship, diagonal interbraces having overlapping ends connected tosaid spars and upper and lower tapering ribs in staggered relationshipconnected to said spars and interbraces.

4. In an aircraft structure upper and lower tapering spars in staggeredrelationship, diagonal interbraces having overlapping ends rivetedtogether, upper and lower tapering ribs in staggered relationship, abolt adapted to fasten said ribs, interbraces and spars together atintersections.

5. In an aircraft structure upper and lower tapering spars in staggeredrelationship, diagonal interbraces having overlapping ends rivetedtogether, bolts fastening said overlapped interbraces to said spars, andupper and lower tapering ribs in staggered relationship fastened to theheads of said bolts.

6. In an aircraft structure upper and lower spars in staggeredrelationship, said spars tapering gradually in. cross section, Z sectiondiagonal interbraces having bent overlapping ends riveted together, abolt adapted to fasten said overlapped ends to the spar, and taperingribs in staggered relationship fastened to the heads of said bolts.

7. In a wing structure a spar of angular cross section, interbracesbearing against the sides of said spar and fastened thereto by means ofa bolt, a transverse rib recessed to fit over said spar and said bolthead and fastened thereto.

8. In a wing structure a spar of angular cross section, interbracesbearing against the sides of said spar and fastened thereto by means ofbolts, a lock washer bent to fit inner angle of said spar, a transverserib recessed to fit over said spar and said bolt heads and fastenedthereto.

9. An aircraft structure comprising spars, longitudinally diagonalinterbraces with overlapped ends, transverse ribs recessed to fit overthe spars and overlapped ends of said interbraces, means for fasteningsaid overlapped ends to said spars and said means also connecting withsaid transverse ribs.

10. A wind-exposed surface for aircraft comprising a structure havingspars tapering in design and thickness, braces holding said spars instaggered relation and a covering of sheet material having one edgesecured to a spar member and another edge of a covering sheetoverlapping said secured edge and fastened only to said sheet.

11. A wind-exposed surface comprising a structure having spars taperingin design and wall thickness, braces holding said spars in staggeredrelationship and a covering over said structure having overlappingedges, one edge being fastened to a spar and the other edge beingfastened only to the covering.

12. A wind exposed surface for aircraft having an internal framing, anda covering of metal sheets, each sheet having one edge in interlockingengagement with the internal framing and the opposite edge secured to anadjacent covering sheet.

13. A wind exposed surface for aircraft comprising a structure havingtapering spars in staggered relation, and a covering of metal sheets,each sheet having one edge in interlocking engagement with a spar, andthe opposite edge secured to an adjacent overlapping sheet of the cover.

14. A wind exposed surface for aircraft comprising a structure havingtapering spars in. staggered relation, and a sheet metal covering forthe structure, each sheet having at its forward edge tabs engaging aspar and its trailing edge attached only to an adjacent overlappingsheet of the covering.

EDMUND B. CARNS.

